Vibration dampening in shipping unit with pallet

ABSTRACT

A shipping unit includes a rack cabinet, computerized devices and a pallet. The computerized devices are mounted within the rack cabinet. The rack cabinet is mounted on the pallet. The pallet includes layers of sheets of structural material and a layer of blocks of vibration dampening padding between first and second ones of the layers of sheets of structural material. Each block of vibration dampening padding includes a lower rectangular portion and an upper tapered portion.

BACKGROUND

Some customers of computers and computer-related products custom order such products with specific desired configurations, e.g. type of processor, amount of memory, number of hard drives, peripheral devices, etc. Additionally, customers may custom order some computers and computer-related products that are designed to be rack mounted within a cabinet for efficient use of vertical space in a room containing such products. If the rack cabinet and desired computers and computer-related products are shipped to the customer separately, then the rack cabinet has to be assembled and the computers and computer-related products have to be installed into the rack cabinet in the room at the customer's site. It is more efficient, however, to assemble the rack cabinet and install the computers and computer-related products at the manufacturing facility and to transport the entire loaded rack cabinet with installed computers and computer-related products as a single shipping unit to the customer's site. In this case, though, due to the size and complexity of the shipping unit and the delicate nature of its components, it is necessary to take special precautions to ensure that the shipping unit arrives at the customer's site undamaged. Such damage may be caused by shock or impact loads due to hitting or dropping the shipping unit or by vibrations due to transportation.

Shipping pallets have been used to transport rack cabinets. The shipping pallets are attached to the bottom of the rack cabinets to form the shipping unit. The shipping pallets are generally made of layers of plywood with a layer of foam to reduce shock and/or attenuate vibration due to transportation of the shipping unit. When dealing with vibration and mass in particular, solutions involving such shipping units depend on the “bearing area” of the layer of foam that is needed to attenuate the vibrations for the given mass. In other words, if there is too much bearing area in the layer of foam between the layers of plywood for a given load of the shipping unit, then the layer of foam will be too stiff to reduce or attenuate shock and vibrations. On the other hand, if there is too little bearing area in the layer of foam for a given load of the shipping unit, then the layer of foam will be too weak to reduce or attenuate shock and vibrations. The shipping pallets are, thus, made to work within a specific weight range for the loaded rack cabinet. For example, a given shipping pallet design might be optimal for use within a weight range of the loaded rack cabinet of only about 800 to 1200 lbs. However, the actual weight for a given loaded rack cabinet may be outside of the specific weight range of the available shipping pallets, since the customer's order may range from a rack cabinet with a single installed computer up to a fully loaded rack cabinet. A given shipping pallet design, therefore, will not work for every possible loaded rack cabinet. It is undesirable, however, to have more than one shipping pallet design in inventory, since having different designs will require more space and cost to accommodate all of the necessary shipping pallet designs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary shipping unit incorporating an embodiment of the present invention.

FIG. 2 is a perspective view of an exemplary shipping pallet for use in the exemplary shipping unit shown in FIG. 1 according to an embodiment of the present invention.

FIG. 3 is an exploded perspective view of the exemplary shipping pallet shown in FIG. 2 incorporating an embodiment of the present invention.

FIG. 4 is a side view of the exemplary shipping pallet shown in FIG. 2 incorporating an embodiment of the present invention.

FIG. 5 is a side view of a first exemplary foam block for use in the exemplary shipping pallet shown in FIG. 2 according to an embodiment of the present invention.

FIG. 6 is a side view of a second exemplary foam block for use in the exemplary shipping pallet shown in FIG. 2 according to an embodiment of the present invention.

FIG. 7 is a side view of a third exemplary foam block for use in the exemplary shipping pallet shown in FIG. 2 according to an embodiment of the present invention.

FIG. 8 is a side view of a fourth exemplary foam block for use in the exemplary shipping pallet shown in FIG. 2 according to an embodiment of the present invention.

FIG. 9 is a side view of a portion of the exemplary shipping pallet shown in FIG. 2 incorporating an embodiment of the present invention.

FIG. 10 is another side view of the portion of the exemplary shipping pallet shown in FIG. 5 incorporating an embodiment of the present invention under a loading condition.

FIG. 11 is yet another side view of the portion of the exemplary shipping pallet shown in FIG. 5 incorporating an embodiment of the present invention under another loading condition.

DETAILED DESCRIPTION

An exemplary shipping unit 100 incorporating an embodiment of the present invention is shown in FIG. 1. The shipping unit 100 generally includes a loaded rack cabinet 102 and a shipping pallet 104. The loaded rack cabinet 102 generally includes devices, such as rack-mounted computers 106 and computer-related products 108 (e.g. network routers/hubs, storage devices, uninterruptible power supplies, blade servers, etc.), mounted within a cabinet 110. The shipping pallet 104 can reduce or attenuate shock and vibration over a weight range of the loaded rack cabinet 102 that can accommodate a variety of configurations of the numbers and types of the devices 106 and 108 within the cabinet 110. Thus, a single design for the shipping pallet 104 can be used for most, if not all, configurations for the loaded rack cabinet 102.

The devices 106 and 108 are generally connected together by a variety of cables 112, typically at a rear side 114 of the cabinet 110. Some or all of the devices 106 and 108 may also be mounted on rails 116 attached to an inside of the cabinet 110, so these devices 106 and 108 can be extended out of a front side 118 of the cabinet 110 for servicing. Although the present invention is described with respect to its use in the shipping unit 100 as shown, it is understood that the invention is not so limited, but may be used in any appropriate shipping unit that requires shock and vibration dampening/attenuation, regardless of the elements included or not included in the shipping unit.

The shipping pallet 104, as shown in FIGS. 2 and 3, includes several layers of plywood (or other appropriate sheet of structural material) 120-134 with a layer of foam (or other appropriate shock and vibration dampening padding or material) 136 in about the middle thereof. The exact number of layers of the plywood 120-134 may depend on the application, so other embodiments may include more or less layers of plywood 120-134 than that shown. The shipping pallet 104 also preferably has holes 137 through which a key hole bracket, or other appropriate engaging device, can engage leveling feet of the cabinet 110 to mount the cabinet 110 to the top layers of the plywood 120-124. Other embodiments may incorporate other mounting methods.

Some of the upper layers of the plywood (e.g. 120, 122 and 124) have length and width dimensions about the same as the overall shipping pallet 104. Lower layers of the plywood (e.g. 126, 128, 130, 132 and 134), on the other hand, are formed of runners 138, 140 and 142. The presence of the layers of the plywood 126-134 with the runners 138-142 allows for a forklift (or other appropriate lifting device) to reach under the upper layers of the plywood 120-124 in order to lift the shipping unit 100.

The top layer of the plywood 120 has one or more masonite hardboards (or other appropriate material) 144 mounted thereon. The masonite hardboards 144 protect the layer of plywood 120 from the loaded rack cabinet 102. Under some situations, the loaded rack cabinet 102 may be so heavy that the bottom of the cabinet 110 would dig into the layer of plywood 120 if the masonite hardboards 144 were not present.

The top layer of the plywood 120 also has various blocks (e.g. wood or other appropriate material) 146 and 148 mounted thereon near the periphery thereof. The various blocks 146 and 148 prevent the cabinet 110 from rolling off the deck when it is being mounted on the shipping pallet 104. There are no such blocks near the rear side 150 of the shipping pallet 104, because the cabinet 110 is typically rolled up onto and back down off of the shipping pallet 104 from this side.

The layers of the plywood 120-134, the various blocks 146 and 148 and the masonite hardboards 144 are attached to each other by any appropriate means, such as by screwing, nailing, gluing, etc. The layer of the foam 136 is preferably attached to the adjacent layers of the plywood (e.g. 126 and 128) by an appropriate means that does not damage the foam material, such as by gluing, etc.

Additionally, bolts 152 are preferably inserted through the shipping pallet 104 (e.g. along the front side 154 and rear side 150 thereof). The bolts 152 are not tightened down to the point of significantly compressing the layer of the foam 136. Instead, the bolts 152 are only screwed down to a point that allows the upper layers of the plywood 120-124 to effectively “float” on the layer of the foam 136 above the lower layers of the plywood 126-134. In this manner, the bolts 152 may hang loose when the shipping pallet 104 is compressed by the weight of the loaded rack cabinet 102. The bolts 152, thus, serve as a safety mechanism that holds the shipping pallet 104 together in the event that it receives a blow that could separate or damage any of the layers 120-136 of the shipping pallet 104.

The layer of the foam 136 may be any appropriate shock and vibration dampening material. An example of such material is Ethafoam™ in a six-pound density available from The Dow Chemical Company. For other embodiments, the exact material and/or density may depend on the anticipated situation. A consideration is that the selected material should be able to be compressed, but should not flatten out too much (as described below) under the highest anticipated load of the loaded rack cabinet 102.

The layer of the foam 136 includes various foam blocks 156-164 (FIGS. 2 and 3). The arrangement of the foam blocks 156-164 within the shipping pallet 104 generally depends on the distribution of the weight of the loaded rack cabinet 102, i.e. of the devices 106 and 108 within the cabinet 110 (FIG. 1). In the example shown, the devices 106 and 108 are generally concentrated near the front side 118 of the cabinet 110, because space near the rear side 114 of the cabinet 110 is generally open to make room for the variety of cables 112. Thus, the center of gravity, or distribution of the weight, of the loaded rack cabinet 102 is typically towards the front side 118 of the cabinet 110. The foam blocks 156-164 (see 156, 160 and 162), therefore, are generally concentrated near the front side 154 of the shipping pallet 104, as shown in FIGS. 3 and 4.

Additionally, the foam blocks 156-160 on the outside runners 138 may be about the same as those on the outside runners 142, as shown, if the weight distribution of the loaded rack cabinet 102 is relatively even from side 166 to side 168 (FIG. 1). On the other hand, if the weight distribution is not relatively even from side 166 to side 168, then the foam blocks 156-160 and the outside runners 138 or 142 on the heavier side may have to be larger, i.e. wider. Furthermore, the foam blocks 162 and 164 on the inside runners 140 down the middle of the shipping pallet 104 are generally larger, i.e. wider, than the other foam blocks 156-160 to account for potential downward bowing of the middle of the upper layers of the plywood 120-126 due to the weight of the loaded rack cabinet 102.

The foam blocks 156-164 used in the exemplary shipping pallet 104 are described herein with respect to FIGS. 5-8. (Foam block 164 has a side view similar to foam blocks 158 shown in FIG. 6.) However, the particular shapes and geometries shown and described for the foam blocks 156-164 are exemplary only. Other embodiments may incorporate foam blocks having different shapes, but with certain preferred features.

The foam blocks 156-164 preferably have a lower generally rectangular portion 170 and at least one upper generally tapered (e.g. trapezoidal) portion 172, as separated by dashed lines 174 in FIGS. 5-8. For the exemplary foam block 156 (FIG. 5), the lower generally rectangular portion 170 is wider than the upper generally tapered portion 172 and extends beyond the width of the upper generally tapered portion 172 in both directions. For the exemplary foam block 158 (FIG. 6), and for the exemplary foam block 164, the lower generally rectangular portion 170 is wider than the upper generally tapered portion 172, but extends beyond the width of the upper generally tapered portion 172 only in one direction. The exemplary foam block 160 (FIG. 7) has two of the upper generally tapered portions 172 spaced apart above the lower generally rectangular portion 170. The exemplary foam block 162 (FIG. 8) has three of the upper generally tapered portions 172 spaced apart above the lower generally rectangular portion 170, with the right-most upper generally tapered portion 172 generally aligning with the upper generally tapered portion 172 of the exemplary foam blocks 156 and the other two upper generally tapered portions 172 generally aligning with the upper generally tapered portions 172 of the exemplary foam blocks 160, as shown in FIGS. 3 and 4.

The top surface 176 of the upper generally tapered portion 172 of the foam blocks 156-164, exemplified by the foam block 156 as shown in FIG. 9, is glued to the runner 138 in the layer of the plywood 126 above. The bottom surface 178 of the lower generally rectangular portion 170 is glued to the runner 138 in the layer of the plywood 128 below.

When the shipping pallet 104 is not loaded, the foam blocks 156-164 have the general shape of the foam block 156 shown in FIG. 9, with little or no deformation. When the shipping pallet 104 is partially loaded, the foam blocks 156-164 have the general shape of the foam block 156 shown in FIG. 10, with some deformation of the lower and upper portions 170 and 172. When the shipping pallet 104 is more heavily loaded, the foam blocks 156-164 have the general shape of the foam block 156 shown in FIG. 11, with considerable deformation of the lower and upper portions 170 and 172.

The upper generally tapered portions 172 of the foam blocks 156-164 generally have a shape that results in the pounds per square inch being about the same (e.g. about 4.5-5.0 psi) for each allowable load on the shipping pallet 104, because the bearing area increases as the load increases. For example, under no load (FIG. 9), i.e. no cabinet 110 on the shipping pallet 104, only the top surface 176 of the foam blocks 156-164 touches the runners 138-142 in the layer of the plywood 126 above. In this example, the bearing area that touches the runners 138-142 above is indicated by dimension A in FIG. 9. In another example, under the loading condition for FIG. 10, i.e. a combination of the cabinet 110 and devices 106 and 108 for a partially loaded rack cabinet 102 on the shipping pallet 104, a portion of the tapered sides of the upper generally tapered portion 172 also touches the runners 138-142 above. In this example, the bearing area that touches the runners 138-142 above is indicated by dimension B, larger than dimension A, in FIG. 10. In yet another example, under the heavier loading condition for FIG. 11, i.e. a combination of the cabinet 110 and devices 106 and 108 for a more heavily loaded rack cabinet 102 on the shipping pallet 104, a larger portion of the tapered sides of the upper generally tapered portion 172 touches the runners 138-142 above. In this example, the bearing area that touches the runners 138-142 above is indicated by dimension C, larger than dimensions A and B, in FIG. 11. Accordingly, the bearing area is generally proportional to the load on the shipping pallet 104, so the psi is generally the same for each load level.

Generally, the necessary vibration/shock attenuation for a larger load is achieved with a larger bearing area of the upper generally tapered portions 172 touching the runners 138-142 in the layer of the plywood 126 above the foam blocks 156-164. Therefore, since the bearing area of the upper generally tapered portion 172 that touches the runners 138-142 above for each of the foam blocks 156-164 depends on the weight of the load in the loaded rack cabinet 102 thereon, the geometry of the foam blocks 156-164 naturally allows for the proper level of vibration/shock attenuation for a wide range in the allowable weight of the loaded rack cabinet 102.

Some portions, i.e. “exposed” portions, of the lower generally rectangular portion 170 of each foam block 156-164 are not directly beneath the upper generally tapered portions 172. It is preferable, however, that only the upper generally tapered portion 172 of each foam block 156-164 touches the runners 138-142 above under “non-shock” loading conditions. This situation allows the exposed portions of the lower generally rectangular portion 170 of each foam block 156-164 to provide additional shock attenuation only when needed. Such need may arise when the shipping unit 100 is subject to a relatively large shock load, e.g. upon accidentally dropping the shipping unit, that causes the upper generally tapered portions 172 to momentarily compress to the point that the exposed portions of the lower generally rectangular portions 170 momentarily touch the runners 138-142 above. When the exposed portions of the lower generally rectangular portions 170 touch the runners 138-142 above, additional shock attenuation is provided. 

1. A shipping unit comprising: a rack cabinet; computerized devices mounted within the rack cabinet; and a pallet on which the rack cabinet is mounted comprising layers of sheets of structural material and a layer of blocks of vibration dampening padding between first and second ones of the layers of the sheets of structural material, each block of vibration dampening padding comprising a lower rectangular portion and an upper tapered portion.
 2. A shipping unit as defined in claim 1, wherein: the upper tapered portion is trapezoidal in cross section.
 3. A shipping unit as defined in claim 1, wherein: the upper tapered portion has a first bearing area contacting the first layer of the sheets of structural material when the pallet is not weighted by the rack cabinet and the computerized devices; and a weight of the rack cabinet and the computerized devices on the pallet causes the blocks of padding to be compressed with a deformation of the upper tapered portion resulting in the upper tapered portion having a second bearing area contacting the first layer of the sheets of structural material, the second bearing area larger than the first bearing area.
 4. A shipping unit as defined in claim 3, wherein: the aforementioned rack cabinet and computerized devices are a first cabinet/devices combination and the weight thereof is a first weight; a second weight of a second cabinet/devices combination on the pallet causes the blocks of padding to be compressed with a deformation of the upper tapered portion resulting in the upper tapered portion having a third bearing area contacting the first layer of the sheets of structural material; and the second weight is larger than the first weight and the third bearing area is larger than the second bearing area.
 5. A shipping unit as defined in claim 4, wherein: the first and second weights are between about 300 and 2000 pounds.
 6. A shipping unit comprising: a means for containing a plurality of computerized devices; a means attached to the containing means for supporting the containing means during transportation thereof; a means within the supporting means for dampening vibration of the containing means, the vibration caused by the transportation of the containing means, the vibration dampening means comprising a lower rectangular portion and an upper tapered portion.
 7. A shipping unit as defined in claim 6, wherein: the upper tapered portion is trapezoidal in cross section.
 8. A shipping unit as defined in claim 7, further comprising: a means within the supporting means for providing structural rigidity to the supporting means and contacting the vibration dampening means; and wherein: the upper tapered portion has a first bearing area contacting the structural rigidity providing means when the supporting means is not weighted by the containing means and the computerized devices; and a weight of the containing means and the computerized devices on the supporting means causes the vibration dampening means to be compressed with a deformation of the upper tapered portion resulting in the upper tapered portion having a second bearing area contacting the structural rigidity providing means, the second bearing area larger than the first bearing area.
 9. A shipping unit as defined in claim 8, wherein: the aforementioned containing means and computerized devices are a first containing-means/devices combination and the weight thereof is a first weight; a second weight of a second containing-means/devices combination on the pallet causes the vibration dampening means to be compressed with a deformation of the upper tapered portion resulting in the upper tapered portion having a third bearing area contacting the structural rigidity providing means; and the second weight is larger than the first weight and the third bearing area is larger than the second bearing area.
 10. A shipping unit as defined in claim 9, wherein: the first and second weights are between about 300 and 2000 pounds.
 11. A pallet for shipping a rack cabinet containing computerized devices, comprising: layers of the sheets of structural material; an engaging device with which the rack cabinet can be mounted to a top one of the layers of the sheets of structural material; and a layer of blocks of vibration dampening padding between first and second ones of the layers of board, each block of padding comprising a lower base portion and an upper tapered portion.
 12. A pallet as defined in claim 11, wherein: the upper tapered portion is trapezoidal in cross section; and the lower base portion is rectangular in cross section.
 13. A pallet as defined in claim 12, wherein: the upper tapered portion has a first bearing area contacting the first layer of board when the pallet is not weighted by the rack cabinet and the computerized devices; the blocks of padding are compressible when the pallet is weighted by the rack cabinet and the computerized devices with a deformation of the upper tapered portion resulting in the upper tapered portion having a second bearing area contacting the first layer of board; and the second bearing area is larger than the first bearing area.
 14. A pallet as defined in claim 13, wherein: the aforementioned rack cabinet and computerized devices are a first cabinet/devices combination and the weight thereof is a first weight; the blocks of padding are compressible when the pallet is weighted by a second weight of a second cabinet/devices combination with a deformation of the upper tapered portion resulting in the upper tapered portion having a third bearing area contacting the first layer of board; and the second weight is larger than the first weight and the third bearing area is larger than the second bearing area.
 15. A pallet as defined in claim 14, wherein: the first and second weights are between about 300 and 2000 pounds.
 16. A method of mitigating vibration on a rack cabinet containing computerized devices and mounted on a pallet, comprising: providing a pallet having layers of board and a layer of blocks of vibration dampening padding between first and second ones of the layers of board, each block of padding comprising a lower base portion and an upper trapezoidal portion; and placing the rack cabinet on the pallet to cause the layer of blocks of padding to be compressed by a weight of the rack cabinet and the computerized devices, the upper trapezoidal portions of the blocks of padding maintaining a gap between the lower base portion and the first layer of board and attenuating vibrations of the rack cabinet and the computerized devices during transportation of the pallet, the rack cabinet and the computerized devices.
 17. A method as defined in claim 16, wherein: when the pallet is not weighted by the rack cabinet and the computerized devices, the upper trapezoidal portion has a first bearing area contacting the first layer of board; when the pallet is weighted by the rack cabinet and the computerized devices, compression of the blocks of padding causes the upper trapezoidal portion to have a second bearing area contacting the first layer of board; and the second bearing area is larger than the first bearing area.
 18. A method as defined in claim 17, wherein: the aforementioned rack cabinet and computerized devices are a first cabinet/devices combination and the weight thereof is a first weight; a second cabinet/devices combination has a second weight greater than the first weight; and when the pallet is weighted by the second cabinet/devices combination, compression of the blocks of padding causes the upper trapezoidal portion to have a third bearing area, larger than the second bearing area, contacting the first layer of board.
 19. A method as defined in claim 18, wherein: the first and second weights are between about 300 and 2000 pounds. 